I have an Amazon 4K Fire Stick (WiFi only) that I got for $24 and it looks pretty good. The sound isn’t so great though, especially on the Hulu app.
When I stream 4K on my blu ray player (Sony UBP-X700) it looks and sounds a little better. Nothing beats putting a 4K UHD disc in it though.
I guess what I’m saying is there’s always a step up, so just take it however you can get it. We are seriously spoiled by the quality and convenience of home theaters now.
All that is missing is my beloved Original Trilogy, properly restored in 4K with HDR.